That was the only solution. And the two extra officials monitoring the goal line wouldn't be needed in every match. Similar to how in baseball, in the regular season there are only 4 umpires in the infield but in the post season there are 6 umpires including two in the outfield down the line. With baseball adopting video reviews in recent years there is now redundancy in having the 2 extra officials for more meaningful matches in the post season, but they still appear.
But prior to video reviews in baseball, the Left Field and Right Field umpires were needed in more important games to ensure accuracy of hits down the line, to see if the ball in or outside the line. Well a similar concept was attempted to be implemented in football with the two extra officials on each goal-line, but like you said, for one reason or another "it didn't seem to achieve anything and it was quickly abandoned".
I would like to explore that statement as it is crucial to understanding how we ended up with VAR. The 2 extra officials monitoring each goal line would theoretically solve every problem that would have caused VAR to be needed.
So why was it abandoned? Because the statement "it didn't seem to achieve anything" is curious, what would there be to achieve other than to provide a "backup" set of eyes to catch what the on-field referee may have missed, which would presumably only be a rare occurrence to which you wouldn't notice them on a match to match basis. But if a howler happened, they could run up to the ref and alert when needed.
Can we pinpoint when this trial took place and how long it lasted for? Were there situations where the extra goal-line official alerted the on-field referee to something he missed? Given the decay of the sport due to VAR and its clear need for the VAR experiment to be put to a halt once and for all, we'll need an alternative to prevent the kinds of errors (the rare howler, etc) that VAR set out to prevent. The two extra officials near the goal-line, maybe not for every match, maybe only for more significant matches, similar to how baseball adds to the two umpires in their post season.
Video review is very harmful to football, on many levels and this is not a satisfactory situation as it presently stands. The idea of two extra officials on the goal-line, for every match, or for only select matches would be a much more practical, less expensive, less aggravating, less controversial, and a more natural solution.
